package miracle.joker.design.singleton;

/*
* 单例模式
* */
public class Singleton {

    private static Singleton instance = null;

    private Singleton(){

    }

        public static Singleton getInstance() {
            if (instance == null){
                instance = new Singleton();
            }
            return  instance;
        }

        public void showMessage(){
            System.out.println("Hello World!");
        }
    }
